Troubleshooting EXP Devices

When an EXP is functioning properly and communicating with the HAL, the Link LED status indicator is green. When an EXP is powered on and connected to the Expansion Bus via shielded CAT 5e cable but cannot communicate with its upstream connection, the LED is off.

note: It is handy to refer to expansion bus connections as being either upstream or downstream in the daisy-chain. An upstream connection is one that is toward the HAL host, which is always the first unit on the expansion bus. As you can guess, a downstream connection is away from the HAL host, toward the other end of the expansion bus.

Use the following steps to troubleshoot EXP communication problems.

1. Follow the daisy-chained expansion bus connections starting at the HAL. Look at each EXP in the downstream direction until you find one which does not display a green Link LED on the front or rear panels.
2. Check the following on this expansion unit:
   • The rear panel Power LED is on.
   • It is connected to the upstream HAL or EXP via shielded CAT 5e (or better) cable.
3. Here are some things to try:
   1. Most likely the cable between the EXP and its upstream device is bad. Try replacing it with a known good shielded CAT 5e cable.
   2. The expansion bus interface on the EXP is not working. Try swapping the expansion bus jacks on the rear of the EXP.
   3. The upstream EXP or HAL expansion bus interface is not working. Try using the other expansion bus jack on the rear of the upstream EXP or HAL.
   4. Try replacing the EXP with another EXP that you know works on the expansion bus - even if temporarily.
   5. Try replacing the upstream EXP or HAL with another device that you know works on the expansion bus.

You can also use Halogen to locate the first EXP that is not connecting properly on the expansion bus. To view the status of the EXP devices on a HAL:

1. Connect to the HAL device to which the EXPs are connected.

2. Click the Hardware tab to open the Hardware Workspace.

3. In the EXP Navigation Panel, look at the title/status bars of the EXP devices configured for the HAL.
4. When the configuration does not match the actual EXP devices connected to the HAL, the device displays yellow warning bars indicating Device Mismatch, Device Unexpected, or Device Missing.. For example, the image below shows that the second EXP in the chain is missing (i.e., the EXP5x is not connected to the Expansion Bus):

   note: When an EXP is missing, all downstream EXPs also indicate Missing status.

5. If all EXPs are present but not connected in the configuration's expected order on the expansion bus, Halogen displays Device Mismatch status for the affected devices. The following image shows that the EXP5x and EXP3x are connected to the expansion bus but not in the correct order:

   In the above example, you should fix the problem by either changing the physical cabling or by swapping the devices in the Halogen Hardware Workspace EXP Navigation Panel. See Swapping Devices for details. We do not recommend selecting the proper EXP devices from the EXP picker (white arrow); although this solves the mismatch problem, it also removes all RAD and/or DR devices from the Processing Workspace. And if the RADs or DRs have settings stored in presets, or a linked to parameters, all these would be lost. Swapping is a better alternative in this case.